Class: Stream::ImplicitStream

Inherits:
BasicStream show all
Defined in:
lib/stream.rb

Overview

An ImplicitStream is an easy way to create a stream on the fly without defining a subclass of BasicStream. The basic methods required for a stream are defined with blocks: 

s = Stream::ImplicitStream.new { |s|

x = 0 s.at_end_proc = proc == 5 s.forward_proc = proc {x += 1 }

}

s.to_a ==> [1, 2, 3, 4, 5]

Note that this stream is only partially defined since backward_proc and at_beginning_proc are not defined. It may as well be useful if only moving forward is required by the code fragment.

ImplicitStreams can be based on other streams using the method modify which is for example used in the methods for creating stream wrappers which remove the first or last element of an existing stream (see remove_first and remove_last).

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Stream

#+, #backward, #collect, #concatenate, #concatenate_collected, #create_stream, #current, #current_edge, #each, #empty?, #filtered, #first, #forward, #last, #modify, #move_backward_until, #move_forward_until, #peek, #remove_first, #remove_last, #reverse, #unwrapped

Methods included from Enumerable

#create_stream

Constructor Details

#initialize(otherStream = nil) {|_self| ... } ⇒ ImplicitStream

Create a new ImplicitStream which might wrap an existing stream otherStream. If otherStream is supplied the blocks for the basic stream methods are initialized with closures that delegate all operations to the wrapped stream.

If a block is given to new, than it is called with the new ImplicitStream stream as parameter letting the client overwriting the default blocks.

Yields:

  • (_self)

Yield Parameters:



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# File 'lib/stream.rb', line 470

def initialize (otherStream=nil)
  if otherStream
	@wrapped_stream = otherStream
	@at_beginning_proc = proc {otherStream.at_beginning?}
	@at_end_proc = proc {otherStream.at_end?}
	@forward_proc = proc {otherStream.basic_forward}
	@backward_proc = proc {otherStream.basic_backward}
	@set_to_end_proc = proc {otherStream.set_to_end}
	@set_to_begin_proc = proc {otherStream.set_to_begin}
  end
  yield self if block_given? # let client overwrite defaults

  @at_beginning_proc = proc {true} unless @at_beginning_proc
  @at_end_proc = proc {true} unless @at_end_proc
end

Instance Attribute Details

#at_beginning_proc=(value) ⇒ Object (writeonly)

Sets the attribute at_beginning_proc

Parameters:

  • value —

    the value to set the attribute at_beginning_proc to.



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# File 'lib/stream.rb', line 460

def at_beginning_proc=(value)
  @at_beginning_proc = value
end

#at_end_proc=(value) ⇒ Object (writeonly)

Sets the attribute at_end_proc

Parameters:

  • value —

    the value to set the attribute at_end_proc to.



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# File 'lib/stream.rb', line 460

def at_end_proc=(value)
  @at_end_proc = value
end

#backward_proc=(value) ⇒ Object (writeonly)

Sets the attribute backward_proc

Parameters:

  • value —

    the value to set the attribute backward_proc to.



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# File 'lib/stream.rb', line 460

def backward_proc=(value)
  @backward_proc = value
end

#forward_proc=(value) ⇒ Object (writeonly)

Sets the attribute forward_proc

Parameters:

  • value —

    the value to set the attribute forward_proc to.



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# File 'lib/stream.rb', line 460

def forward_proc=(value)
  @forward_proc = value
end

#set_to_begin_proc=(value) ⇒ Object (writeonly)

Sets the attribute set_to_begin_proc

Parameters:

  • value —

    the value to set the attribute set_to_begin_proc to.



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# File 'lib/stream.rb', line 460

def set_to_begin_proc=(value)
  @set_to_begin_proc = value
end

#set_to_end_proc=(value) ⇒ Object (writeonly)

Sets the attribute set_to_end_proc

Parameters:

  • value —

    the value to set the attribute set_to_end_proc to.



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# File 'lib/stream.rb', line 460

def set_to_end_proc=(value)
  @set_to_end_proc = value
end

#wrapped_stream ⇒ Object (readonly)

Returns the value of attribute wrapped_stream.



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# File 'lib/stream.rb', line 461

def wrapped_stream
  @wrapped_stream
end

Instance Method Details

#at_beginning? ⇒ Boolean

Returns the value of @at_beginning_proc.

Returns:

  • (Boolean) 


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# File 'lib/stream.rb', line 487

def at_beginning?; @at_beginning_proc.call; end

#at_end? ⇒ Boolean

Returns the value of @at_end_proc.

Returns:

  • (Boolean) 


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# File 'lib/stream.rb', line 489

def at_end?; @at_end_proc.call; end

#basic_backward ⇒ Object

Returns the value of @backward_proc_proc.



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# File 'lib/stream.rb', line 494

def basic_backward; @backward_proc.call; end

#basic_forward ⇒ Object

Returns the value of @forward_proc.



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# File 'lib/stream.rb', line 492

def basic_forward; @forward_proc.call; end

#set_to_begin ⇒ Object

Calls set_to_begin_proc or super if set_to_begin_proc is undefined.



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# File 'lib/stream.rb', line 502

def set_to_begin
  @set_to_begin_proc ? @set_to_begin_proc.call : super
end

#set_to_end ⇒ Object

Calls set_to_end_proc or super if set_to_end_proc is undefined.



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# File 'lib/stream.rb', line 497

def set_to_end
  @set_to_end_proc ? @set_to_end_proc.call : super
end